In a wide variety of technologies, the ability and/or facility in separating matter, typically particulate matter, from a fluid is a critical component in the ability to test for the presence of substances in the fluid. For example, laboratories are now able to use infra-red spectroscopy to determine the presence of cancer cells, but the utility of this technique is hampered by the difficulty in sample preparation. Too often, interference associated with sample preparation obscures the target cells to such a degree that the process is not sufficiently reliable, or too costly.
A similar scenario applies to many other fields which involve detection and/or diagnosis, including environmental testing, radiation research, cancer screening, cytological examination, microbiological testing, and hazardous waste contamination, to name just a few.
In all of these endeavors, a limiting factor in the sample preparation protocol is adequately separating solid matter from its fluid carrier (e.g., a variety of fluids, such as physiological, biological and environmental), and in easily and efficiently collecting and concentration the solid matter in a form readily accessible to electromagnetic radiation. For example, it has been reported that infra red technology can be used to differentiate between malignant cells and normal cells. The cells exhibit a characteristic absorbance wavelength which may be used to identify the presence and type of cell and its quantity. The sample preparation processes involves painstakingly isolating the target cells from tissue or body fluids, then passing an infra-red beam through a support which holds the cell sample. In a typical process, the cells must be collected and smeared on a support, such as a microscope slide. The collection and transfer requires some degree of skill, and even then, a cell smear may not be suitable for analysis using infra red technology.
Diagnostic microbiology and/or cytology, particularly in the area of clinical pathology, bases diagnoses on a microscopic examination of cells and other microscopic analyses. The accuracy of the diagnosis and the preparation of optimally interpretable specimens typically depends upon adequate sample preparation.
The present invention is based in part on the relatively new development of using electromagnetic radiation, such as infrared radiation, to characterize matter. For example, an infra red beam may be passed through some type of support which holds solid matter, such as cells, in a predetermined position. By passing the beam through the solid matter, the solid matter absorbs a characteristic wavelength within the beam; this absorbance can be measured. This measurement, and the characteristic absorbance pattern may be used to identify the type and quantity of the solid matter present in the sample and its molecular make-up or composition.
As noted above, however, any electromagnetic protocol is limited by the manner in which the sample is prepared. The present invention provides an easy, quick, cost efficient, reproducible, and superior process and apparatus for collecting the solid matter suitable for analysis using electromagnetic radiation.
The present invention provides a stark contrast to the various sample preparation techniques typically used. In the cast film method, the sample is dissolved in a solvent, the solution is added dropwise to an infra red window material (KBr or Csl), and the solution is allowed to evaporate, forming a thin film on the window material. In some cases, the thin film must be removed from the window material and placed on an inert solid support prior to exposure to infra red radiation.
In the hot press film technique, polymeric samples are carefully melted between two infra red salt plates (KBr or Csl), carefully pressing one of the plates against the other until a thin film is formed. In a similar technique, a liquid smear is formed by pressing a viscous fluid sample until a capillary film is produced.
In the potassium bromide pellet technique, the sample is ground to a particle size of about one micron, the sample is mixed with infra red grade KBr (carefully, to insure homogeneity), and the powder mixture is pelletized using high pressure.
Low concentration samples may also be prepared using pyrolysis, e.g., forming a dry distillation of a liquid distillate.
It should be readily apparent that for each of these infra red analysis sample preparation protocols, significant manipulation of the sample is required. Furthermore, the sample must be transferred to a solid support or window material (KBr, Csl, glass, aluminum foil, or a mercury surface), materials which sometimes interfere with the sample absorbance pattern.